Submitted on October 16, 2007
Accepted on February 5, 2008
Molecular Mechanism of ADP-Ribosyl Cyclase Activation in Angiotensin II Signaling in Murine Mesangial Cells
Seon-Young Kim1, Rukhsana Gul1, So-Young Rah1, Suhn Hee Kim2, Sung Kwang Park3, Mie-Jae Im1, Ho Jeong Kwon4, and Uh-Hyun Kim1*
1 Biochemistry, Chonbuk National University Medical School, Jeonju, Chonbuk , Korea, Republic of
2 Physiology, Chonbuk National University Medical School, Jeonju, Chonbuk , Korea, Republic of
3 Internal Medicine, Chonbuk National University Medical School, Jeonju, Chonbuk , Korea, Republic of
4 Biotechnology, College of Engineering, Yonsei University, Seoul, Seoul, Korea, Republic of
* To whom correspondence should be addressed. E-mail: uhkim{at}chonbuk.ac.kr.
ADP-ribosyl cyclase (ADPR-cyclase) produces a Ca2+-mobilizing second messenger, cyclic ADP-ribose (cADPR) from NAD+. In this study, we investigated molecular basis of ADPR-cyclase activation and the following cellular events in angiotensin II (AngII) signaling in mouse mesangial cells (MMCs). Treatment of MMCs with AngII induced an increase in intracelluar Ca2+ concentrations through a transient Ca2+ release via IP3 receptor and a sustained Ca2+ influx via L-type Ca2+ channels. The sustained Ca2+ signal, but not the transient Ca2+ signal, was blocked by a cADPR antagonistic analog, 8-Br-cADPR and an ADPR-cyclase inhibitor, 4,4’-dihydroxyazobenzene (DHAB). Supporting the results, AngII stimulated cADPR production in a time dependent manner, and DHAB inhibited AngII-induced cADPR production. Application of pharmacological inhibitors revealed that activation of ADPR-cyclase by AngII involved AngII type 1 receptor, phosphoinositide 3-kinase, protein tyrosine kinase, and phospolipase C-
1. Moreover, DHAB as well as 8-Br-cADPR abrogated AngII-mediated Akt phosphorylation, nuclear translocation of nuclear factor of activated T-cell, and uptake of [3H]-thymidine and [3H]-leucine in MMCs. These results demonstrate that ADPR-cyclase in MMCs plays a pivotal role in AngII signaling for cell proliferation and protein synthesis.
